Exam 4 lecture

Question 1

Conventional (type II) myosins generate what?
and what do the head and tails do?

Answer 1

motility
Head (catalytic sites) required for motor activity
* The tail portion allows protein to form filaments

Question 2

Why are actin-binding filaments important?

Answer 2

these actin-binding proteins are important for how the actin is going to be arranged and how the filaments can interact with one another
Ex: -maintaining cell structure, enabling cellular motility and transport, mediating cell-cell and cell-matrix interactions, and regulating various cellular processes essential for life.

Question 3

lamellipodium

Answer 3

flat broad membranous protrusions located at the leading edge of the migrating cells. Lamellipodia determine the cell movement direction by protrusive force that arises from the actin network. This network is formed as a result of actin filament polymerization against the plasma membrane.

Question 4

What is the process of directed cell motility when a stimulus is received?

Answer 4

1. stimulus being received
2. The WASP is activated and its function is to activate Arp2/3
3. Arp2/3 serves as a site for actin to form/ arrange
4. activated complexes(WASP and Arp2/3) initiate nucleation of actin polymerization
5. Side branches form, complexes push plasma membrane outward

Question 5

Microspikes

Answer 5

point outward to the edge of lamellipodium

Question 6

Filopodia

Answer 6

elongations that extend and retract during motile activity

Question 7

Changes in cell shape during development:

Answer 7

1. cells elongate- occurs bc microtubules orient in a particular way
2. cells constrict- the result of bringing everything up
3. They constrict even more and the curves in- the development of the neural tube that gives arise to the nervous system

Question 8

In embryonic development, cells in an epithelium become constricted on one end and thus become wedge-shaped. What is the effect of this change in cells on the epithelium as a whole?
a) It stretches out b) It contracts
c) It narrows
d) It curves inward

Answer 8

d) It curves inward

Question 9

Neutrophils are a type of white blood cell that acts as your immune systems first line of defence.
What would result if there was a mutation in a gene that made WASP in a neutrophil?

Answer 9

The WASP would not activate Arp 2/3 to get actin to rearrange, resulting in the cell not moving and patients being immunocompromised.